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Search found 233 results on 10 pages for 'finite automata'.

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• How to recover from finite-state-machine breakdown?

  - by Earl Grey

  My question may seems very scientific but I think it's a common problem and seasoned developers and programmers hopefully will have some advice to avoid the problem I mention in title. Btw., what I describe bellow is a real problem I am trying to proactively solve in my iOS project, I want to avoid it at all cost. By finite state machine I mean this I have a UI with a few buttons, several session states relevant to that UI and what this UI represents, I have some data which values are partly displayed in the UI, I receive and handle some external triggers (represented by callbacks from sensors). I made state diagrams to better map the relevant scenarios that are desirable and alowable in that UI and application. As I slowly implement the code, the app starts to behave more and more like it should. However, I am not very confident that it is robust enough. My doubts come from watching my own thinking and implementation process as it goes. I was confident that I had everything covered, but it was enough to make a few brute tests in the UI and I quickly realized that there are still gaps in the behavior ..I patched them. However, as each component depends and behaves based on input from some other component, a certain input from user or some external source trigers a chain of events, state changes..etc. I have several components and each behave like this Trigger received on input - trigger and its sender analyzed - output something (a message, a state change) based on analysis The problem is, this is not completely selfcontained, and my components (a database item, a session state, some button's state)...COULD be changed, influenced, deleted, or otherwise modified, outside the scope of the event-chain or desirable scenario. (phone crashes, battery is empty phone turn of suddenly) This will introduce a nonvalid situation into the system, from which the system potentially COULD NOT BE ABLE to recover. I see this (althought people do not realize this is the problem) in many of my competitors apps that are on apple store, customers write things like this "I added three documents, and after going there and there, i cannot open them, even if a see them." or "I recorded videos everyday, but after recording a too log video, I cannot turn of captions on them.., and the button for captions doesn't work".. These are just shortened examples, customers often describe it in more detail..from the descriptions and behavior described in them, I assume that the particular app has a FSM breakdown. So the ultimate question is how can I avoid this, and how to protect the system from blocking itself? EDIT I am talking in the context of one viewcontroller's view on the phone, I mean one part of the application. I Understand the MVC pattern, I have separate modules for distinct functionality..everything I describe is relevant to one canvas on the UI.

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• How to perform FST (Finite State Transducer) composition

  - by Tasbeer

  Consider the following FSTs : T1 0 1 a : b 0 2 b : b 2 3 b : b 0 0 a : a 1 3 b : a T2 0 1 b : a 1 2 b : a 1 1 a : d 1 2 a : c How do I perform the composition operation on these two FSTs (i.e. T1 o T2) I saw some algorithms but couldn't understand much. If anyone could explain it in a easy way it would be a major help. Please note that this is NOT a homework. The example is taken from the lecture slides where the solution is given but I couldn't figure out how to get to it.

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• Can an object oriented program be seen as a Finite State Machine?

  - by Peretz

  This might be a philosophical/fundamental question, but I just want to clarify it. In my understanding a Finite State Machine is a way of modeling a system in which the system's output will not only depend on the current inputs, but also the current state of the system. Additionally, as the name suggests it, a finite state machine can be segmented in a finite N number of states with its respective state and behavior. If this is correct, shouldn't every single object with data and function members be a state in our object oriented model, making any object oriented design a finite state machine? If that is not the interpretation of a FSM in object design, what exactly people mean when they implement a FSM in software? am I missing something? Thanks

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• Make a steady automata in javascript

  - by RobertWHurst

  I'm working on a javascript game and I've got an automata system controlling game time and sprite animation as well as giving a hand to the path finding system for timing and such. My problem is on slow browsers the javascript loop I'm using for counting the time is not very accurate. It tends to jump around a lot. I there a way to force the loop to run consistantly at 30 fps? The automata can drop frames if it needs to catch up so if the solution requires droping frames thats ok.

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• Is a finite state machine an appropriate solution for this situation?

  - by user1936

  I was writing some test code as an example where I had a washing machine class. It has a door state that should be open or closed, and also a running state, either on or off. I want to prevent the running state from changing from 'off' to 'on' when the door is 'open', and also prevent the door from being set to 'open' while the machine is 'on'. I have this functionality rigged up with a bunch of if statements. It feels inelegant and it could quickly turn into spaghetti code if I want to add another state that puts additional conditions on the changes of other states. I wonder, is a finite state machine a solution for this situation? Would it simplify adding states and defining valid transitions?

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• Code Golf: Finite-state machine!

  - by Adam Matan

  Finite state machine A deterministic finite state machine is a simple computation model, widely used as an introduction to automata theory in basic CS courses. It is a simple model, equivalent to regular expression, which determines of a certain input string is Accepted or Rejected. Leaving some formalities aside, A run of a finite state machine is composed of: alphabet, a set of characters. states, usually visualized as circles. One of the states must be the start state. Some of the states might be accepting, usually visualized as double circles. transitions, usually visualized as directed arches between states, are directed links between states associated with an alphabet letter. input string, a list of alphabet characters. A run on the machine begins at the starting state. Each letter of the input string is read; If there is a transition between the current state and another state which corresponds to the letter, the current state is changed to the new state. After the last letter was read, if the current state is an accepting state, the input string is accepted. If the last state was not an accepting state, or a letter had no corresponding arch from a state during the run, the input string is rejected. Note: This short descruption is far from being a full, formal definition of a FSM; Wikipedia's fine article is a great introduction to the subject. Example For example, the following machine tells if a binary number, read from left to right, has an even number of 0s: The alphabet is the set {0,1}. The states are S1 and S2. The transitions are (S1, 0) -> S2, (S1, 1) -> S1, (S2, 0) -> S1 and (S2, 1) -> S2. The input string is any binary number, including an empty string. The rules: Implement a FSM in a language of your choice. Input The FSM should accept the following input: <States> List of state, separated by space mark. The first state in the list is the start state. Accepting states begin with a capital letter. <transitions> One or more lines. Each line is a three-tuple: origin state, letter, destination state) <input word> Zero or more characters, followed by a newline. For example, the aforementioned machine with 1001010 as an input string, would be written as: S1 s2 S1 0 s2 S1 1 S1 s2 0 S1 s2 1 s2 1001010 Output The FSM's run, written as <State> <letter> -> <state>, followed by the final state. The output for the example input would be: S1 1 -> S1 S1 0 -> s2 s2 0 -> S1 S1 1 -> S1 S1 0 -> s2 s2 1 -> s2 s2 0 -> S1 ACCEPT For the empty input '': S1 ACCEPT For 101: S1 1 -> S1 S1 0 -> s2 s2 1 -> s2 REJECT For '10X': S1 1 -> S1 S1 0 -> s2 s2 X REJECT Prize A nice bounty will be given to the most elegant and short solution. Reference implementation A reference Python implementation will be published soon.

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• Language to grammar in this automata

  - by rahul

  help me to solve this problem anbncn where n=1

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• Finite State Machine Spellchecker

  - by Durell

  I would love to have a debugged copy of the finite state machine code below. I tried debugging but could not, all the machine has to do is to spell check the word "and",an equivalent program using case is welcomed. #include<cstdlib> #include<stdio.h> #include<string.h> #include<iostream> #include<string> using namespace std; char in_str; int n; void spell_check() { char data[256]; int i; FILE *in_file; in_file=fopen("C:\\Users\\mytorinna\\Desktop\\a.txt","r+"); while (!feof(in_file)) { for(i=0;i<256;i++) { fscanf(in_file,"%c",in_str); data[i]=in_str; } //n = strlen(in_str); //start(data); cout<<data; } } void start(char data) { // char next_char; //int i = 0; // for(i=0;i<256;i++) // if (n == 0) { if(data[i]="a") { state_A(); exit; } else { cout<<"I am comming"; } // cout<<"This is an empty string"; // exit();//do something here to terminate the program } } void state_A(int i) { if(in_str[i] == 'n') { i++; if(i<n) state_AN(i); else error(); } else error(); } void state_AN(int i) { if(in_str[i] == 'd') { if(i == n-1) cout<<" Your keyword spelling is correct"; else cout<<"Wrong keyword spelling"; } } int main() { spell_check(); system("pause"); return 0; }

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• Problem with creating a deterministic finite automata (DFA) - Mercury

  - by Jabba The hut

  I would like to have a deterministic finite automata (DFA) simulated in Mercury. But I’m s(t)uck at several places. Formally, a DFA is described with the following characteristics: a setOfStates S, an inputAlphabet E <-- summation symbol, a transitionFunction : S × E -- S, a startState s € S, a setOfAcceptableFinalStates F =C S. A DFA will always starts in the start state. Then the DFA will read all the characters on the input, one by one. Based on the current input character and the current state, there will be made to a new state. These transitions are defined in the transitions function. when the DFA is in one of his acceptable final states, after reading the last character, then will the DFA accept the input, If not, then the input will be is rejected. The figure shows a DFA the accepting strings where the amount of zeros, is a plurality of three. Condition 1 is the initial state, and also the only acceptable state. for each input character is the corresponding arc followed to the next state. Link to Figure What must be done A type “mystate” which represents a state. Each state has a number which is used for identification. A type “transition” that represents a possible transition between states. Each transition has a source_state, an input_character, and a final_state. A type “statemachine” that represents the entire DFA. In the solution, the DFA must have the following properties: The set of all states, the input alphabet, a transition function, represented as a set of possible transitions, a set of accepting final states, a current state of the DFA A predicate “init_machine (state machine :: out)” which unifies his arguments with the DFA, as shown as in the Figure. The current state for the DFA is set to his initial state, namely, 1. The input alphabet of the DFA is composed of the characters '0'and '1'. A user can enter a text, which will be controlled by the DFA. the program will continues until the user types Ctrl-D and simulates an EOF. If the user use characters that are not allowed into the input alphabet of the DFA, then there will be an error message end the program will close. (pred require) Example Enter a sentence: 0110 String is not ok! Enter a sentence: 011101 String is not ok! Enter a sentence: 110100 String is ok! Enter a sentence: 000110010 String is ok! Enter a sentence: 011102 Uncaught exception Mercury: Software Error: Character does not belong to the input alphabet! the thing wat I have. :- module dfa. :- interface. :- import_module io. :- pred main(io.state::di, io.state::uo) is det. :- implementation. :- import_module int,string,list,bool. 1 :- type mystate ---> state(int). 2 :- type transition ---> trans(source_state::mystate, input_character::bool, final_state::mystate). 3 (error, finale_state and current_state and input_character) :- type statemachine ---> dfa(list(mystate),list(input_character),list(transition),list(final_state),current_state(mystate)) 4 missing a lot :- pred init_machine(statemachine :: out) is det. %init_machine(statemachine(L_Mystate,0,L_transition,L_final_state,1)) :- <-probably fault 5 not perfect main(!IO) :- io.write_string("\nEnter a sentence: ", !IO), io.read_line_as_string(Input, !IO), ( Invoer = ok(StringVar), S1 = string.strip(StringVar), (if S1 = "mustbeabool" then io.write_string("Sentenceis Ok! ", !IO) else io.write_string("Sentence is not Ok!.", !IO)), main(!IO) ; Invoer = eof ; Invoer = error(ErrorCode), io.format("%s\n", [s(io.error_message(ErrorCode))], !IO) ). Hope you can help me kind regards

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• how useful is Turing completeness? are neural nets turing complete?

  - by Albert

  While reading some papers about the Turing completeness of recurrent neural nets (for example: Turing computability with neural nets, Hava T. Siegelmann and Eduardo D. Sontag, 1991), I got the feeling that the proof which was given there was not really that practical. For example the referenced paper needs a neural network which neuron activity must be of infinity exactness (to reliable represent any rational number). Other proofs need a neural network of infinite size. Clearly, that is not really that practical. But I started to wonder now if it does make sense at all to ask for Turing completeness. By the strict definition, no computer system nowadays is Turing complete because none of them will be able to simulate the infinite tape. Interestingly, programming language specification leaves it most often open if they are turing complete or not. It all boils down to the question if they will always be able to allocate more memory and if the function call stack size is infinite. Most specification don't really specify this. Of course all available implementations are limited here, so all practical implementations of programming languages are not Turing complete. So, what you can say is that all computer systems are just equally powerful as finite state machines and not more. And that brings me to the question: How useful is the term Turing complete at all? And back to neural nets: For any practical implementation of a neural net (including our own brain), they will not be able to represent an infinite number of states, i.e. by the strict definition of Turing completeness, they are not Turing complete. So does the question if neural nets are Turing complete make sense at all? The question if they are as powerful as finite state machines was answered already much earlier (1954 by Minsky, the answer of course: yes) and also seems easier to answer. I.e., at least in theory, that was already the proof that they are as powerful as any computer.

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• Finite Numbers and ExplorerCanvas

  - by PhubarBaz

  I was working on my online mathematical graphing application, CloudGraph, and trying to make it work in IE. The app uses the HTML5 canvas element to draw graphs. Since IE doesn't support canvas yet I use ExplorerCanvas to provide that support for IE. However, it seems that when using excanvas, if you try to moveTo or drawTo a point that is not finite it loses it's mind and stops drawing anything else after that. I had no such problems in Firefox or Chrome so it took me awhile to figure out what was going on. Next I discovered that I needed a way to check if a variable was NaN or Inifinity or any other non-finite value so I could avoid calling moveTo() in that case. I started writing a long if statement, then I thought there has to be a better way. Sure enough there was. There just happens to be an isFinite() function built into Javascript just for this purpose. Who knew! It works great. Another difference I discovered with excanvas is that you must specify a starting point using a moveTo() when beginning a drawing path. Again, Chrome and Firefox are a lot more forgiving in this area so it took me a while to figure out why my lines weren't drawing. But, all is happy now and I'm a little wiser to the ways of the canvas.

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• finite state machine used in mario like platform game

  - by juakob

  I dont understand how to use a finite state machine with the entity controlled by the player. For example i have a mario(2d platform) i can jump,run,walk,take damage,swim,etc so my first thought was to use this actions as states. But what happen when you are running when you take damage? or jumping taking damage and shooting at the same time? I just want to add functionalities(actions) to the player in a clean way(not using ifs for all the actions in the entity update)

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• Python — Time complexity of built-in functions versus manually-built functions in finite fields

  - by stackuser

  Generally, I'm wondering about the advantages versus disadvantages of using the built-in arithmetic functions versus rolling your own in Python. Specifically, I'm taking in GF(2) finite field polynomials in string format, converting to base 2 values, performing arithmetic, then output back into polynomials as string format. So a small example of this is in multiplication: Rolling my own: def multiply(a,b): bitsa = reversed("{0:b}".format(a)) g = [(b<<i)*int(bit) for i,bit in enumerate(bitsa)] return reduce(lambda x,y: x+y,g) Versus the built-in: def multiply(a,b): # a,b are GF(2) polynomials in binary form .... return a*b #returns product of 2 polynomials in gf2 Currently, operations like multiplicative inverse (with for example 20 bit exponents) take a long time to run in my program as it's using all of Python's built-in mathematical operations like // floor division and % modulus, etc. as opposed to making my own division, remainder, etc. I'm wondering how much of a gain in efficiency and performance I can get by building these manually (as shown above). I realize the gains are dependent on how well the manual versions are built, that's not the question. I'd like to find out 'basically' how much advantage there is over the built-in's. So for instance, if multiplication (as in the example above) is well-suited for base 10 (decimal) arithmetic but has to jump through more hoops to change bases to binary and then even more hoops in operating (so it's lower efficiency), that's what I'm wondering. Like, I'm wondering if it's possible to bring the time down significantly by building them myself in ways that maybe some professionals here have already come across.

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• How can I make a steady automata in JavaScript?

  - by RobertWHurst

  I'm working on a JavaScript game and I've got an automata system controlling game time and sprite animation as well as giving a hand to the path finding system for timing and such. My problem is on slow browsers the JavaScript loop I'm using for counting the time is not very accurate. It tends to jump around a lot. I there a way to force the loop to run consistently at 30 fps? The automata can drop frames if it needs to catch up so if the solution requires dropping frames that's ok.

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• Finite state machine in C++

  - by Electro

  So, I've read a lot about using FSMs to do game state management, things like what and FSM is, and using a stack or set of states for building one. I've gone through all that. But I'm stuck at writing an actual, well-designed implementation of an FSM for that purpose. Specifically, how does one cleanly resolve the problem of transitioning between states, (how) should a state be able to use data from other states, and so on. Does anyone have any tips on designing and writing a implementation in C++, or better yet, code examples?

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• Modeling player mechanics with a finite state machine

  - by K..

  I have three states standing walking jumping When I press D standing transitions to walking. The velocity will be set to a defined value and the player moves. When I release D walking transitions back to standing, which sets the velocity back to 0. When I press W and the state is walking it transitions to jumping, but when the player hits the ground, it goes back to standing. jumping has a transition land that always leads to standing because a state doesn't know about its previous states. Since standing sets a velocity of 0 the player stops walking, when he hits the ground. How do I prevent this?

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• Why does my finite state machine take so long to execute?

  - by BillyONeal

  Hello all :) I'm working on a state machine which is supposed to extract function calls of the form /* I am a comment */ //I am a comment perf("this.is.a.string.which\"can have QUOTES\"", 123456); where the extracted data would be perf("this.is.a.string.which\"can have QUOTES\"", 123456); from a file. Currently, to process a 41kb file, this process is taking close to a minute and a half. Is there something I'm seriously misunderstanding here about this finite state machine? #include <boost/algorithm/string.hpp> std::vector<std::string> Foo() { std::string fileData; //Fill filedata with the contents of a file std::vector<std::string> results; std::string::iterator begin = fileData.begin(); std::string::iterator end = fileData.end(); std::string::iterator stateZeroFoundLocation = fileData.begin(); std::size_t state = 0; for(; begin < end; begin++) { switch (state) { case 0: if (boost::starts_with(boost::make_iterator_range(begin, end), "pref(")) { stateZeroFoundLocation = begin; begin += 4; state = 2; } else if (*begin == '/') state = 1; break; case 1: state = 0; switch (*begin) { case '*': begin = boost::find_first(boost::make_iterator_range(begin, end), "*/").end(); break; case '/': begin = std::find(begin, end, L'\n'); } break; case 2: if (*begin == '"') state = 3; break; case 3: switch(*begin) { case '\\': state = 4; break; case '"': state = 5; } break; case 4: state = 3; break; case 5: if (*begin == ',') state = 6; break; case 6: if (*begin != ' ') state = 7; break; case 7: switch(*begin) { case '"': state = 8; break; default: state = 10; break; } break; case 8: switch(*begin) { case '\\': state = 9; break; case '"': state = 10; } break; case 9: state = 8; break; case 10: if (*begin == ')') state = 11; break; case 11: if (*begin == ';') state = 12; break; case 12: state = 0; results.push_back(std::string(stateZeroFoundLocation, begin)); }; } return results; } Billy3

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• A compiler for automata theory

  - by saadtaame

  I'm designing a programming language for automata theory. My goal is to allow programmers to use machines (DFA, NFA, etc...) as units in expressions. I'm confused whether the language should be compiled, interpreted, or jit-compiled! My intuition is that compilation is a good choice, for some operations might take too much time (converting NFA's to equivalent DFA's can be expensive). Translating to x86 seems good. There is one issue however: I want the user to be able to plot machines. Any ideas?

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• How should I design a wizard for generating requirements and documentation

  - by user1777663

  I'm currently working in an industry where extensive documentation is required, but the apps I'm writing are all pretty much cookie cutter at a high level. What I'd like to do is build an app that asks a series of questions regarding business rules and marketing requirements to generate a requirements spec. For example, there might be a question set that asks "Does the user need to enter their age?" and a follow-up question of "What is the minimum age requirement?" If the inputs are "yes" and "18", then this app will generate requirements that look something like this: "The registration form shall include an age selector" "The registration form shall throw an error if the selected age is less than 18" Later on down the line, I'd like to extend this to do additional things like generate test cases and even code, but the idea is the same: generate some output based on rules determined by answering a set of questions. Are there any patterns I could research to better design the architecture of such an application? Is this something that I should be modeling as a finite state machine?

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• Need theoretical help, how to comprehend an if-else dependency net

  - by macbie

  I am going to face a following issue: I'm writing a program that manages some properties, some of them are general and some are specific. Each property is a pair of key and value, and for example: if it is given a general property and other specific property with exactly the same key and value has been existed before then the general property will swap the specific one in the register. If there are two the same general properties - both will remain in the register. And so on; it is like a net of dependencies. In my case I can handle with it intuitively and foresee all cases, but only because the system is not too vast. What if it would? I have met such problems a few times in many different programs and languages (i.e working with C semaphores) and my question is: How to approach this kind of problem? Is this connected with finite state machine, graph theory or something similar? How to be sure that I have considered the whole system and each possible case? Could you recommend some resources (books, sites) to learn from?

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• Is this a good implementation of a loop in Prolog?

  - by Carles Araguz

  First of all, let me tell you that this happens to be the first time I ask something here, so if it's not the right place to do so, please forgive me. I'm developing a rather complex software that has a Prolog core implementing a FSM. Since I don't want it to stop (ever), I'm trying to write a good loop-like predicate that would work using Prolog's recursion. After a few unsuccessful tries (mainly because of stack problems) I ended up having something similar to this: /* Finite State Transition Network */ transition(st0,evnt0,st1). transition(st1,evnt1,st2). transition(st2,evnt2,st0). fsm_state(state(st0),system(Energy,ActivePayloads),[]) :- /* ... */ transition(st0,evnt0,NextState), !, fsm_state(state(NextState),system(Energy,ActivePayloads),[]). fsm_state(state(st1),system(Energy,ActivePayloads),[]) :- /* ... */ transition(st1,evnt1,NextState), !, fsm_state(state(NextState),system(Energy,ActivePayloads),[0,1,2]). fsm_state(state(st2),system(Energy,ActivePayloads),[P|Params]) :- /* ... */ transition(st2,evnt2,NextState), !, fsm_state(state(NextState),system(Energy,ActivePayloads),[]). start :- Sys = system(10,[]), fsm_state(state(s0),Sys,[]). Is this a good approach?

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• Best Practise/Subjective: Implement a finite state automaton in OOP

  - by poeschlorn

  Hi guys, I am thinking about implementing a programm with finite state automaton in an OOP language like Java or C++. What would you think is the best way to implement this with a manageable amount of available states, regarding to good software design? Is it good to implement for each state an own class? If yes, how to do the bridge between two states? Thanks for any comment!

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• Finite State Machine : Bad design?

  - by f4

  Are Finite State Machines generally considered as bad design in OOP ? I hear that a lot. And, after I had to work on a really old, undocumented piece of C++ making use of it, I tend to agree. It was a pain to debug. what about readability/maintainability concerns?

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• Visualize flowchart diagram with multiple end symbols

  - by platzhirsch

  I am looking for a standardize way to visualize the following hierarchical logic: The state of the thread is represented by the answers to the hierarchical set of question You can read this listing like a flowchart, you iterate over the questions decide, go one step deeper and so on. Therefore I thought the best way to visualize it, using a flowchart. The problem is, in this hierarchical set it is possible to end in more than one state and its totally valid. I have never seen a flowchart where you can enter more than one state. Is it still possible and I am missing the right symbol to present this logic or are flowchart not fitting anyway? What other graphical representation could I use, is there something fitting in UML? A non-deterministic state machine seems not to be intuitive enough, transfering it into a deterministic state machine would result in to many states, and so on.

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• Visualize flowchart diagram with multiple end symbols

  - by platzhirsch

  I am looking for a standardize way to visualize the following hierarchical logic: The state of the thread is represented by the answers to the hierarchical set of question You can read this listing like a flowchart, you iterate over the questions decide, go one step deeper and so on. Therefore I thought the best way to visualize it, using a flowchart. The problem is, in this hierarchical set it is possible to end in more than one state and its totally valid. I have never seen a flowchart where you can enter more than one state. Is it still possible and I am missing the right symbol to present this logic or are flowchart not fitting anyway? What other graphical representation could I use, is there something fitting in UML? A non-deterministic state machine seems not to be intuitive enough, transfering it into a deterministic state machine would result in to many states, and so on.

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